Frequently Asked Questions

Will A Kimberly™ Stove Make My Tiny House Too Warm?

Tiny house builders often ask if the Kimberly™ wood stove will produce too much heat for a tiny house.  The answer to this is you can control the amount of heat that Kimberly™ will produce by the amount of wood you add at any given time and the frequency with which you reload Kimberly™.

In the Kimberly™ wood stove, there are two separate combustion zones.  The lower combustion zone is where the wood burns very slowly, deliberately creating lots of smokey gases which then rise to the upper part of the combustion chamber. There, the gases ignite and burn before exiting the chimney.

A tiny house owner with a Kimberly™ stove would simply add less wood per load, and load Kimberly™ less often than would the owner of a bigger home who needed more heat:

Less wood ==> Less wood gas ==> Less secondary combustion ==> Less heat




What Are Expected Burn Times In A Kimberly™ Stove?

Unforgettable Fire, LLC approximates burn time in a Kimberly™ stove as being up to 8 hours, coal bed to coal bed. Understand that your choice of fuel and moisture content will affect your burn time and heat output, as will the user’s understanding of the “sweet spot” on the damper control. The more wood gas that is produced in primary combustion by restricting the oxygen, the longer the burn time in the secondary combustion.

  • Will you wake up to active flames in the morning? {No}
    Will you wake up to a warm stove and chimney and live coals, making it easy to get your fire going again? {Likely yes, depending on fuel}

How warm your house will be after the Kimberly™ has not been refueled for a period of time will be determined by one or more variables:

  • Local climate and weather conditions.
  • Square footage and ceiling height of your space.
  • Insulation in your walls and attic.
  • Window quality and number of windows.
  • Location of your wood stove within your space.
  • Air movement & humidity levels within your space.
  • Wood species and wood moisture content of your fuel.

Understand that hard woods will burn longer and produce less creosote than will soft woods, and that dry, seasoned wood will burn longer and produce less creosote than wood containing greater than 20% moisture.

Your investment in a moisture meter with an accuracy of +/- 1% can be made for less than $50 and it will help to ensure you are getting the most heat and longest burn times from the least amount of wood.

How Do I Vent the Kimberly™ Wood Stove?

Our Kimberly™ wood stove is approved to use 3-inch double-wall stainless steel pellet stove pipe with a Class A pass-through thimble at the ceiling, attic and roof.

This unique venting system saves owners hundreds of dollars in installation costs, perhaps as much as $1500 in savings, simply because pellet stove pipe is far less costly than using Class A chimney pipe for the entire length of the chimney as other wood stoves require.

See the Kimberly™ Owner’s Manual for specific instructions on venting in your Kimberly™ wood stove in your tiny house or contact us for further information regarding your specific needs.

Can I Vent Kimberly™ Horizontally Instead of Vertically?

In Roger Lehet’s 28 years of selling and installing wood stoves, he has always preferred to vent straight through the roof at all times. There are few instances where this becomes impossible due to construction styles, but this is rare.

Kimberly™ is unique in that she is the only wood stove (to our knowledge) which is approved to vent with 3-inch stainless steel pellet stove pipe with an appropriate Class A pass-through thimble. This is due to exceptionally low flue temperatures.

You will notice in the Kimberly™ Owner’s Manual that there is no approved through-the-wall installation instructions. When one vents out a wall, the cost of installation increases substantially. As well, the flue is exposed to cold outside air, which can cool the exhaust temperatures and can negatively impact the performance of the chimney. This method also allows heat to be transferred to the outside, rather than kept inside the home where it belongs.

Furthermore, horizontal runs can further impede the performance of the chimney during start-up (when the chimney is cold) causing smoke-back to become an issue.

Whenever possible, always install your venting vertically inside the house, through the ceiling and roof.

What Kind of Fuel Can Kimberly™ Burn?

The Kimberly™ stove is a wood stove and therefore designed to burn regular cordwood. As well, many people choose to burn extruded logs because they are convenient. Never burn sawdust logs which contain waxes or paraffins.

Remember to always burn wood that has 20% moisture content or less and verify it with a moisture meter. Hard wood that has been well seasoned will produce far more heat and far less creosote than soft wood or wet wood.

What Size Logs Can I Burn?

Kimberly™ can accommodate one log of 4-inches across and up to 9.5-inches in length. However, in our personal experience, we like to cut our wood shorter to allow sufficient room for a coals. We find that wood which is cut from 4-inches to 6-inches in length and the pieces stacked on top of each other is easier to load than a single longer log.

If your tiny house is well insulated, it is likely that the temperature inside your tiny house will require you to load only one short log at a time.

How Does Kimberly’s BTU Output Compare With Others?

By definition, a British Thermal Unit (BTU) is the amount of energy needed to heat one pound of water by one degree Fahrenheit. BTU’s are commonly used to describe the energy content of fuels and are used as a loose standard of comparison for the heat output from heating appliances such as propane furnaces and wood stoves.

While BTU/hour ratings may be fairly consistent when shopping for propane furnaces, BTU/hour ratings mean very little when shopping for a wood stove.

In theory, one would think that wood stoves with a higher BTU/hour rating would produce more heat than lower rated units. However, BTU/hour test protocols do vary, causing a great deal of confusion for the general public. Therefore, to fully understand a particular wood stove’s BTU/hour rating, one must first understand the test protocol which produced it.

First of all, it is critical to realize that the EPA test protocol for wood stoves was established to measure emissions, not a BTU/hour heat output. The EPA emissions test protocol is standardized to burn milled pine lumber of the same size, shape, and moisture content, relative to the size of the firebox for each stove. The EPA emissions test protocol requires that each stove’s draft control be set to its lowest and smokiest setting.

Therefore, the BTU/hour measured during an EPA emissions test will always be lower than what would be produced if burning a firebox full of seasoned hardwood fueled by oxygen from a more open draft. It is for this reason that the following disclaimer appears on every EPA label in upper case letters:


It is therefore misleading for one to compare the BTU/hour heat output of one wood stove against another wood stove, because the BTU/hour ratings are not the subject of the EPA emissions test, and are therefore not trustworthy. Furthermore, other test protocols are not standardized.

Comparing BTU/hour ratings on wood stoves would be like comparing apples to oranges and oranges to bananas. While they are all fruits, they are all very different from one another.

How A Gasifier Wood Stove Differs From A Rocket Stove?

Kimberly™ {and her bigger sister, Katydid™} are gasifier wood stoves, not rocket stoves.

When a Kimberly™ or Katydid™ wood stove is dampered down, the fuel maintains an approximate 450-degree Fahrenheit temperature as it burns, thus creating massive amounts of smoky gases. As the smokey gases rise to the top of the combustion chamber in a Kimberly™ or Katydid™ wood stoves, the gasses ignite and burn at a very high temperature.

The bulk of the heat produced in our Kimberly™ and Katydid wood stoves comes from the secondary combustion process, which produces a very efficient and clean burn, with very little smoke to no emitting from the chimney.

While rocket stoves burn very hot and very clean, they are not efficient. Rocket stoves are hungry and consume lots of fuel.

Which Is Better, A Catalytic Or Non-Catalytic Wood Stove?

Given the very nature of catalytic wood stoves, they are perhaps more suited to people who enjoy gadgets and technology, and are sufficiently disciplined to maintain a catalytic wood stove properly, so as to maximize performance and longevity. Even then, catalytic elements, when spent, must be disposed of, causing an unnecessary burden to our landfills.

In catalytic wood stoves, smoke flows through a coated ceramic honeycomb device, inside the firebox, where smoke particles and gases ignite and burn. This is comparable to the catalytic converter on your car. Even though catalytic stoves are capable of producing long and even heat output, there are many disadvantages to this technology.

First, many owners of catalytic wood stoves find that they need to “babysit” a catalytic wood stove until it heats sufficiently to activate the catalytic element.

Second, if at any time a catalytic wood stove is over-fired, or fueled with inappropriate material (such as burning treated wood or household trash), the catalyst may fail in as little as two years. Compare that to the six years which can be expected from a well maintained catalytic stove using only appropriate fuels.

Even under the best of conditions the catalytic element will degrade, and require replacement, which is not inexpensive. Burning paper printed with colored inks or a a piece of wood with a stray nail will render the catalyst immediately useless.

Third, the mining and processing of catalytic elements is costly to the environment, not to mention there are the political considerations and risks of mining the catalytic elements in the volatile Middle East.

Kimberly™ and Katydid™ are non-catalytic wood stoves. Unforgettable Fire, LLC has developed the means to produce catalytic action from a non-catalytic stove by use of gasification technology.

Our non-catalytic Kimberly™ gasifier wood stove was EPA certified at 3.2 grams per hour particulate, well under the Washington State emissions standards of 4.5 grams/hour. Even more remarkable, our Katydid™ gasifier wood stove was EPA certified at 1.9 grams/hour, making Katydid™ one of the cleanest wood burning stoves available today.

Is Your Kimberly™ Wood Stove EPA / CSA Certified?

Our Kimberly™ wood stove is EPA / CSA certified and UL-Listed. In addition, Kimberly™ is EPA certified for use in Washington State, which has the most stringent emission standards in the United States.

Kimberly™ provides an exceptionally clean burn, emitting 3.2 grams/hour in EPA testing, as compared 7.5 grams/hour allowed by federal EPA standards, and 4.5 grams/hour allowed by Washington State standards.


When Will The Optional Accessories Be Available?

The optional Cobb Oven & Grill and Stove Lite thermo-electric lantern are currently available for purchase.

A thermo-electric generator is under development for Kimberly™. Sadly, we have no information on a release dates or pricing at this time.

Because the accessories are optional additions, you can confidently buy your Kimberly™ wood stove without delay.

Kindly contact us to be notified when additional accessories become available for purchase.

What Is The Warranty On A Kimberly™ Stove?

Unforgettable Fire, LLC offers a five-year, non-prorated warranty to the original purchaser of a Kimberly™  or Katydid™ wood stove heater on all parts, except for replacement glass, replacement gaskets, replacement grate/ash pan covers, misuse or abuse, or improper installation. At its sole discretion, Unforgettable Fire, LLC will either repair or replace any defective unit to the original purchaser under these terms. The original purchaser shall be responsible for all shipping and handling costs associated with any warranty claims.

Why Are Kimberly™ Wood Stoves So Costly?

When considering the price of a new wood stove, one should always look at total installation costs, not just the cost of the stove itself. Even a “free” wood stove can quickly become a $2,000 investment by the time one adds in the cost of Class A chimney pipe, hearth pad, shipping, and installation labor.

With that said, Kimberly™ is actually competitive with other high end wood stoves. OK – you pay more for the Kimberly™ stove itself, but you pay less to vent it, and in the end, your total installation costs may actually be less money than a stove costing half as much as Kimberly™.

Why? This is because Kimberly™ is approved to vent with double-wall stainless steel pellet stove pipe, which is far less costly than Class A chimney pipe.

Furthermore, the versatility of Kimberly™ can allow a resident of a tiny house the freedom to omit other appliances. Remember that when the Lehet family lived on their boat in Puget Sound, their Kimberly™ wood stove was the only appliance that the family had in their boat. Kimberly™ kept the family warm, dry, clean, and well fed.

Your investment in Kimberly™ can be recouped in as little as two years over less environmentally friendly options such as propane, electric, or oil heat, because cordwood is inexpensive or free, while gas, electric or oil heat will continue to extract from your wallet for years to come.

Kimberly™ has a five-year non-prorated warranty. That means your warranty holds the same value in Year Five as it did in Year One.

Unforgettable Fire, LLC is a small manufacturer and does not experience the advantage of purchasing raw materials in larger quantities that bigger manufacturers enjoy. There are approximately 118 laser cut and hand-welded parts inside, which are made from domestic feed stock by American workers, all of whom pay taxes and support our American economy. Six years were devoted to Kimberly’s research and development; the certification testing alone cost $40,000, and it will be some time before these costs are recouped.

Quality does not come cheap in this world, and the folks at Unforgettable Fire, LLC refuse to produce any product that is less than world class.